1. Field of the Invention
The present invention relates generally to apparatuses and methods for filtering intravascular fluids and for delivering diagnostic and therapeutic agents into a living organism. The invention includes embodiments of various shapes and structures that are used to infuse therapeutic agents or deliver such agents intravascularly in the form of a soluble coating, and other embodiments that circulate or contain a preloaded charge of radioactive material for intravascular radiotherapy. The invention further includes embodiments for filtering intravascular fluids using filtration devices placed within the living organism.
2. Description of the Related Art
Atherosclerosis is a cardiovascular disease in which deposits of plaques (atheromas) containing cholesterol, lipid material, foam cells, lipophages and proliferating smooth muscle cells are within the intima and media of large to small diameter arteries such as the aorta and the iliac, femoral, coronary and cerebral arteries. The resultant stenosis causes a reduction in blood flow.
Attempts to treat atherosclerosis have included bypass surgery wherein the diseased vascular segments are augmented by prosthetic or natural grafts. This procedure requires general anesthesia and a substantial healing period after surgery and, thus, is generally limited to cases of severe coronary artery disease.
Other approaches for the recanalization of stenotic vessels include percutaneous transluminal coronary angioplasty (PTCA), atherectomy, stenting and newer modalities of cardiovascular intervention, including laser angioplasty. The primary drawbacks of these procedures has been the appearance of restenosis at or near the site of the original stenosis in the blood vessel that requires a secondary angioplasty procedure or a bypass surgery. Another occurrence that reduces the success of a typical angioplasty procedure is that frequently the stenotic plaque or intima of the blood vessel or both are dissected during the angioplasty procedure by the inflation of the balloon. Upon the deflation of the balloon, a section of the dissected lining (commonly termed xe2x80x9cflapxe2x80x9d) will collapse into the bloodstream, thereby closing or significantly reducing the blood flow through the vessel. In these instances, emergency bypass surgery is often required to avoid a myocardial infarct distal to the blockage.
In recent years, various devices and methods (other than bypass surgery) for prevention of restonosis and for repairing damaged blood vessels have become known. These methods typically use an expandable cage or region (commonly termed xe2x80x9cstentxe2x80x9d) on the distal end of a catheter designed to hold a detached lining against an arterial wall for extended periods to facilitate the reattachment thereof. Some stents are designed for permanent implantation inside the blood vessel, and others are designed for temporary use inside the vessel.
Typically, the expandable region of the prior art stents is formed by a braided wire or balloon attached to the distal end of the catheter body. Such designs are difficult and expensive to manufacture, and create reliability concerns due to the existence of high stress points located at the connection of the braided wire region with the catheter body and at the connections between the intermingled wire strands.
Alternatively, or in addition to the use of stents, various drugs have been applied to the site of the dilated lesion to prevent or reduce chances of restenosis and to aid in the healing of flaps, dissection or other hemorrhagic conditions that may appear after an angioplasty procedure. The prior art braided wire and balloon stents, as disclosed, for example, in U.S. Pat. Nos. 4,655,771, 5,295,962, 5,368,566 and 5,421,826, cannot be used to deliver or inject fluid-based agents to the specific site of the lesion while maintaining adequate flow in the vascular lumen. The fluid flow through the lumen is substantially blocked by these stents during use.
In recognition of this problem, temporary stenting catheters with drug delivery capabilities have been developed, as disclosed, for example, in U.S. Pat. Nos. 5,383,928 and 5,415,637. The ""928 patent discloses a coil-shaped stent covered by a polymer sheath for local drug delivery. A drug is incorporated into the polymer sheath for controlled release of the drug upon insertion. Because the polymer sheath itself is as large as the diameter of the coil, the device cannot be removed from the subject outside of the lab and without a guiding catheter. Moreover, the device is limited in its ability to adapt to the shape and size of the vessel wall, and in that only drugs that are compatible with and can be incorporated into the polymer can be delivered by the device.
The temporary stenting catheter of the ""637 patent functions to hold a collapsed dissected lining or flap against the blood vessel wall for a sufficient time to allow the natural adhesion of the flap to the blood vessel wall. The stenting catheter of the ""637 patent also functions to introduce a drug to the site of the vascular procedure to aid in the adhesion process and in the prevention of restenosis while allowing the flow of blood through the vessel to locations distal to the catheter.
The catheter assembly of the ""637 patent, however, has a number of disadvantages. The catheter assembly is complex and expensive to manufacture. More importantly, however, the catheter assembly of the ""637 is very expensive to use because it requires a guiding catheter to be maintained within the vessel and the patient to be maintained within the catheter lab during use and deployment.
There are other known devices, as disclosed, for example, in U.S. Pat. Nos. 4,531,933, 4,694,838, 4,813,925, 4,887,996, and 5,163,928, that use a catheter having a heat set polymer stent at a distal end shaped as a halo or coil. These devices require pushing a rod through the lumen of the heat set curve in the polymer to straighten the device so that it may be inserted into the body through a guide catheter. The rod is then removed and the curve shape of the catheter comes back. These devices suffer from being limited in size due to the fact that a relatively large wire must be used to straighten the device (e.g., 0.014xe2x80x3 to 0.016xe2x80x3). Thus, the lumen size of these devices are correspondingly large. The devices also suffer from a lack of ability to be deformed (i.e., coiled, bent, or shaped) without permanent deformation. Because of the permanent deformation, the devices fail to track the inside of a vessel that is not round.
The prior art drug delivery systems cannot be left in place for a period of time outside the lab in which the angioplasty was performed, and then removed by a nurse by simply pulling the system out. Any coil that relies on a balloon for its intravascular shape requires inflation to maintain the coil""s shape, and the patient is required to stay in the lab under fluoro to make sure the coil stays in place. Any coil that relies on the modules of the polymer to maintain the coil shape is too rigid to pull out and requires the use of a straightening rod to push through the coil so that the coil straightens out before removal. This procedure would not be permitted outside the catheter lab, thus, adding significant cost to the procedure.
Another method of preventing or controlling restenosis following angioplasty has been developed in recent years which uses intravascular radiotherapy (IRT). IRT may also be used to prevent stenosis following cardiovascular graft procedures or other trauma to the vessel wall. IRT involves introducing a radioactive material, such as a beta emitting material (for example, 32P) or a photon emitting material (for example, 125I), into a blood vessel for a predetermined time to provide a radiation dosage. The radiation dosage must be carefully controlled to impair or arrest hyperplasia without causing excessive damage to healthy tissue. Overdosing of a section of blood vessel can cause arterial necrosis, inflammation and hemorrhaging, while under dosing will result in no inhibition of smooth muscle cell hyperplasia, or even exacerbation of the hyperplasia and resulting restenosis.
An IRT method using a radioactive stent is disclosed in U.S. Pat. No. 5,059,166. The radioactive stent is designed to be permanently implanted in the blood vessel after completion of a lumen opening procedure. The radiation dose delivered to the patient is determined by the activity of the stent at the particular time it is implanted.
Another IRT method is disclosed in U.S. Pat. No. 5,302,168, which uses a radioactive source contained in a flexible carrier with remotely manipulated windows. This method generally requires the use of a higher activity source than the radioactive stent to deliver an effective dose to the patient. Accordingly, measures must be taken to ensure that the source is maintained at the center of the lumen to prevent localized overexposure of tissue to the radiation source. Use of a higher activity source also requires expensive shielding and other equipment for safe handling. Conventional IRT methods also tend to block or restrict blood flow through the vessel during treatment.
Thus, there is a need for an improved system and method for delivering diagnostic and therapeutic agents intravascularly that overcomes the problems of the existing systems. There is also a need for an improved system and method for filtering intravascular fluids with filtration devices that can be deployed and removed efficiently and without blocking fluid flow through the vessel during treatment.
It is an object of the present invention to provide a method and system for delivering diagnostic and therapeutic agents intravascularly that overcomes the problems in the above-mentioned prior art.
It is a further object of the present invention to provide a delivery system for delivering diagnostic and therapeutic agents with an extremely soft coil shape for engaging a vessel.
It is a further object of the present invention to provide a delivery system for diagnostic and therapeutic agents that can be removed from the body without the use of guiding catheters or introduction devices, and that can be left in place for a period of time outside the lab where it was installed and removed by simply pulling it out.
It is a further object of the present invention to provide a delivery system for diagnostic and therapeutic agents that is very small and flexible, and that has an improved ability to track the inside of a vessel and to be deformed (i.e., coiled, bent, or shaped) without permanent deformation.
It is a further object of the present invention to provide a coil-shaped delivery system with the above advantages that has a radiopaque polymer tubing or radiopaque coating over a polymer tubing for observation under a fluoroscope or other X-ray device.
It is a further object of the present invention to provide a coil-shaped delivery system having multiple lumens for delivering fluid-based agents and/or withdrawing fluid samples.
It is a further object of the present invention to provide a coil-shaped delivery system having a number of different shapes to suit a particular application.
It is a further object of the present invention to provide a coil-shaped delivery system having an inner sheath to guide diagnostic and therapeutic agents to a wall of a vessel.
It is yet a further object of the present invention to provide a coil-shaped delivery system having a soluble coating on the surface of a coil that dissolves when placed in a body fluid in a vessel.
It is a still further object of the present invention to provide a coil-shaped delivery system that can be deployed by introducing a pressure through the lumen of the coil that causes the coil to unwind and expand in diameter against the wall of the vessel.
It is a still further object of the present invention to provide a coil-shaped delivery system that has telescoping, concentric support tubes connected to respective ends of the coil that can be manipulated in a push-pull or twist manner to change the diameter and length of the coil to provide precise deployment.
It is a further object of the present invention to provide an apparatus shaped by a resilient fiber core and having a return line or vent tube for introducing or circulating a suspension of radioactive material within a vessel to provide intravascular radiotherapy.
It is a still further object of the present invention to provide an apparatus shaped by a resilient fiber core and preloaded with a radioactive material for use in intravascular radiotherapy.
It is a still further object of the present invention to provide a system for intravascular radiotherapy including an apparatus preloaded with a radioactive material and a protective container for transporting the preloaded apparatus to minimize handling and exposure of radioactive components by the user.
It is a still further object of the present invention to provide a system for filtering fluids intravascularly that can be deployed and removed easily and efficiently without blocking a flow of fluid through the vessel, and that can be used to introduce therapeutic agents upstream or downstream of the filtration structure.
Additional objects, advantages, and novel features of the invention will be set forth in the following description, and will become apparent to those skilled in the art upon reading this description or practicing the invention. The objects and advantages of the invention may be realized and attained by the appended claims.
To achieve the foregoing and other objects and in accordance with the purpose of the present invention, as embodied and broadly described herein, the coil apparatus of the present invention comprises a resilient fiber core having a linear portion and a coiled portion, and a polymer tubing encasing the resilient fiber core and adapting to the shape of the resilient fiber core, the polymer tubing comprising a first portion encasing the linear portion of the resilient fiber core and a second portion encasing the coiled portion of the resilient fiber core.
In one embodiment, the polymer tubing has a lumen extending along a length of the polymer tubing, and the second portion of the polymer tubing comprises means for releasing a fluid-based agent delivered through the lumen from the coil apparatus. The releasing means may comprise a series of openings spaced along the second portion of the polymer tubing, or a porous, braided, or stitched material of the polymer tubing.
The polymer tubing may comprise multiple lumens for delivering fluid-based agents and/or withdrawing fluid samples. Moreover, an inner sheath may be secured to the polymer tubing to guide fluid-based agents to a wall of a vessel in which the coil is deployed.
In an alternative arrangement, an outer surface of the coiled portion of the polymer tubing is covered with a soluble coating containing a therapeutic agent. The soluble coating is then dissolved when the coil is placed in a body fluid contained in a vessel. In another arrangement, a first portion of the polymer tubing is covered with a soluble coating containing a therapeutic agent, and a second portion of the polymer tubing has a releasing means for delivering fluid-based agents from a lumen of the polymer tubing.
In another embodiment, the apparatus is formed with a vent tube or return passage for allowing a suspension of radioactive material to be introduced and/or circulated through a portion of the polymer tubing after it is deployed in a vessel. A polymer tubing with a return passage can be formed using a double lumen tubing having distal ends of the lumens connected together, or by using a single lumen tubing having both ends of the coiled portion connected to respective linear portions of the tubing. Alternatively, a vent tube can be inserted into a lumen of a polymer tubing to permit a radioactive suspension to be introduced into the lumen while air is being vented out of the lumen. A deployment sheath formed of a high density material or having a high density liner is provided to protect the vessel from incidental radiation when the apparatus is being deployed in or removed from the vessel.
In another embodiment, a radioactive material is preloaded into the apparatus to minimize handling and exposure of radioactive components by the user. The preloaded apparatus is then loaded into a deployment sheath and placed in a protective container formed of a high density material or with a lead liner to prevent radiation exposure during shipping and handling before and after the apparatus is deployed in a vessel for treatment. The preloaded apparatus can have a wider variety of shapes and structures since there is no need for a supply or return passage.
In yet another embodiment, the portion of the device preloaded with a radioactive material is formed as a separate member from rest of the device and is connected to the device before deployment using a suitable fitting. The portion of the device containing the radioactive material can then be kept in a separate protective container from the rest of the device, thus facilitating handling of the radioactive components.
The radioactive material can be in the form of a liquid suspension, a powder, encapsulated balls, or the like placed within the coiled portion. Alternatively, the coiled portion can be exposed to a radiation source for a predetermined time to make the wire core or another material preloaded into the device radioactive.
With the construction of the present invention, the apparatus can be extremely small. For example, the resilient fiber core can be formed of a metallic steel heat-tempered spring alloy, such as a titanium-nickel-chromium alloy, or a boron fiber having a diameter of 0.001 to 0.006 inches. The polymer tubing can have an outside diameter of 0.003 to 0.014 inches and an inside diameter of 0.002 to 0.008 inches. The polymer tubing is preferably formed of a very soft material, such as nylon, urethane, PE and TFE polymer materials, and has a Shore D hardness of approximately 40 so as to minimize resistance to the preformed shape of the resilient fiber core and prevent damage to a vessel during use. The polymer tubing is constructed of a polymer compounded with a radio opacifier at a loading high enough to make the polymer radiopaque.
In a first embodiment, the coiled portion of the resilient fiber core is shaped into a forward feed coil shape extending away from the linear portion of the resilient fiber core.
In a second embodiment, the resilient fiber core is shaped into a reverse feed coil shape with a bent transition portion between the linear portion and the coiled portion, the bent transition portion directing the coiled portion in a reverse direction back along the linear portion.
In additional embodiments, the coiled portion of the resilient fiber core is shaped into a forward feed coil shape extending away from the linear portion of the resilient fiber core and includes a distal end portion that can be engaged by a catheter for deployment purposes.
The resilient fiber core may also be pre-shaped in a number of different shapes to suit a particular application. For example, the resilient fiber core may be spiral-shaped in plan view, or helical-shaped with a tapered diameter.
In a further aspect of the present invention, in accordance with its objects and purposes, the present invention comprises a combination of a coil apparatus for delivering diagnostic and therapeutic agents intravascularly and an apparatus for deploying the coil apparatus at a desired location in a vessel, the coil apparatus comprising a resilient fiber core having a linear portion and a coiled portion, and a polymer tubing encasing the resilient fiber core and adapting to the shape of the resilient fiber core, the polymer tubing comprising a first portion encasing the linear portion of the resilient fiber core and a second portion encasing the coiled portion of the resilient fiber core.
The apparatus for deploying the coil apparatus comprises a delivery sheath, the delivery sheath having an inside diameter that is smaller than a preset diameter of the coiled portion for compressing the coil apparatus during deployment.
In one embodiment, the apparatus for deploying the coil apparatus further comprises a push tube for pushing the coil apparatus out of the delivery sheath during deployment, the push tube being slidable over a linear portion of the coil apparatus.
In another embodiment, the apparatus for deploying the coil apparatus further comprises a deployment catheter that is slidable over the coil apparatus, the deployment catheter comprising a slotted distal end for receiving the bent transition portion of the coil apparatus to permit pushing and twisting of the coil apparatus during deployment.
In other embodiments, the apparatus for deploying the coil apparatus further comprises a deployment catheter having a means for holding the distal end portion to permit pushing and twisting of the coil apparatus during deployment. The holding means may comprise a notch and snare or other suitable holding structure across a distal end of the deployment catheter for receiving and holding the distal end portion of the infusion coil apparatus. Alternatively, the holding means may utilize a friction lock formed in the distal end of the deployment catheter into which the distal end portion of the infusion coil apparatus can be inserted and securely held during deployment.
In another embodiment, a first marker is provided at a forward distal end of the deployment catheter and a second marker is spaced axially rearwardly from the first marker. The first and second markers are radiopaque for determining placement of the infusion coil apparatus within a vessel. The first and second markers are spaced apart a distance equal to an axial length of the coiled portion in a relaxed position of the coiled portion.
According to another embodiment of the present invention, the deployment apparatus is further provided with a proximal holding tube positioned over a linear portion of the infusion coil. The proximal holding tube has a distal end abutting a coiled portion of the infusion coil and is secured to the infusion coil. The proximal holding tube permits manipulation of the infusion coil during deployment using the proximal holding tube in conjunction with the deployment catheter.
In another embodiment of the present invention, the delivery sheath of the deployment apparatus further comprises a guide tube extending from a point adjacent a distal end of the delivery sheath to an opening in a side wall of the delivery sheath. The guide tube is secured to the side wall of the delivery sheath and has an inner diameter large enough to permit a guide wire to pass therethrough.
In a further aspect of the present invention, in accordance with its objects and purposes, the present invention comprises a method for delivering diagnostic and therapeutic agents into a vessel, comprising the steps of providing an infusion coil apparatus having a resilient fiber core encased by a soft polymer tubing, loading the infusion coil apparatus into a delivery sheath, the delivery sheath having an internal diameter which is smaller than a preset diameter of a coiled portion of the resilient fiber core, inserting the delivery sheath and the infusion coil apparatus into a vessel, and pushing the infusion coil apparatus out of the delivery sheath whereby the resilient fiber core causes the infusion coil apparatus to increase in diameter and lodge in the vessel. The method further comprises the step of feeding a fluid-based agent through the polymer tubing of the infusion coil apparatus into the vessel, or the step of covering an outer surface of the coiled portion of the polymer tubing with a soluble coating containing a therapeutic agent.
In one embodiment of the present invention, the method further comprises the steps of sliding a push tube over a linear portion of the infusion coil apparatus, pushing the infusion coil apparatus out of the delivery sheath using the push tube, and removing the push tube and the delivery sheath from the vessel while maintaining the infusion coil apparatus within the vessel.
In another embodiment of the present invention, the method further comprises the steps of providing the infusion coil apparatus with a reverse feed coil shape with a bent transition portion between a linear portion and a coiled portion, the bent transition portion directing the coiled portion in a reverse direction back along the linear portion, providing a deployment catheter having a slotted distal end, sliding the deployment catheter over the infusion coil apparatus and receiving the bent transition portion of the infusion coil apparatus in the slotted distal end of the deployment catheter.
In other embodiments of the present invention, the method further comprises the steps of providing the infusion coil apparatus with a forward feed coil shape extending away from a linear portion of the resilient fiber core, and a distal end portion, providing a deployment catheter having a holding structure in a distal end of the deployment catheter, and receiving and securing the distal end portion of the infusion coil apparatus in the holding structure of the deployment catheter.
The method may further comprise the steps of pushing the infusion coil apparatus out of the delivery sheath into the vessel with the deployment catheter, and twisting the deployment catheter to rewind the infusion coil apparatus into a deployed position against a wall of the vessel. The method also may include the steps of providing first and second radiopaque marks on the deployment catheter, the first and second marks being spaced apart a distance approximately equal to an axial length of the coiled portion in a relaxed position of the infusion coil apparatus, and twisting the deployment catheter to rewind the infusion coil apparatus until the axial length of the coiled portion is approximately the same as the distance between the first and second marks.
In another embodiment of the present invention, the method for delivering diagnostic and therapeutic agents further comprises the steps of providing the infusion coil apparatus with a forward feed coil shape extending away from a linear portion of the resilient fiber core, providing a proximal holding tube over a linear portion of the infusion coil, the proximal holding tube having a distal end abutting a coiled portion of the infusion coil, the proximal holding tube being secured to the infusion coil, sliding the proximal holding tube and the deployment catheter in opposite directions to elongate and reduce the diameter of a coiled portion of the infusion coil apparatus, placing the elongated coil into the delivery sheath, pushing the infusion coil apparatus out of the delivery sheath into the vessel using the deployment catheter and the proximal holding tube, and sliding the proximal holding tube and the deployment catheter in opposite directions to compress and increase the diameter of the coiled portion of the infusion coil apparatus, whereby the infusion coil apparatus is placed in a deployed position against a wall of the vessel.
In another embodiment of the present invention, the method further comprises the steps of providing a guide tube within the delivery sheath, the guide tube having a first distal end adjacent to a distal end of the delivery sheath, and a second proximal end in communication with an opening through a side wall of the delivery sheath, and sliding the guide tube over a guide wire to facilitate the step of inserting the delivery sheath and the infusion coil apparatus into a vessel.
In another embodiment of the present invention, a coil apparatus is deployed by placing a coiled portion of the apparatus in a vessel to be treated, and introducing a pressure into the lumen of the coiled portion to cause the coiled portion to unwind and expand in diameter within the vessel.
In yet another embodiment of the present invention, a precise deployment method is provided using a pair of telescoping, concentric support tubes connected to respective ends of the coiled portion of the apparatus, and manipulating the concentric support tubes to change the length and/or diameter of the coiled portion.